1. Field of the Invention
The present invention relates to a packaging technology of a light-sensing element, particularly to a packaging structure of a light-sensing element and a fabrication method thereof, which can protect the light-sensing chip from the pollution by external particles.
2. Description of the Related Art
A CMOS light-sensing element is an element fabricated according to the principle of optoelectronics and is extensively used in the image-related field, such as security cameras, digital cameras, toys, mobile phones, PDA's, video phones, fingerprint identifiers, etc.
Refer to from FIG. 1A to FIG. 1C for the steps of the conventional fabrication method of a CMOS light-sensing element. Firstly, as shown in FIG. 1A, a substrate 10 having metallization traces 12 is provided; a frame 14 is stuck onto the perimeter of the substrate 10 with a first glue layer 16; a light-sensing chip 20 is stuck onto the substrate 10 with an adhesive 18 and positioned inside the frame 14, and the light-sensing chip 20 has a light-sensing region 22. Next, as shown in FIG. 1B, a wire-bonding procedure is undertaken, and multiple bond wires 24 are used to electrically connect the light-sensing chip 20 to the metallization traces 12 of the substrate 10; then, a cleaning procedure is undertaken to remove pollutants. Next, as shown in FIG. 1C, a transparent glass 28 is joined to the frame 14 with a second glue layer 26, and the packaging structure of a light-sensing element shown in FIG. 1C is thus formed. Such a packaging method can retard external pollutants, and the CMOS light-sensing element can truly sense the surroundings thereby.
As the frame 14 has been joined to the substrate 10 before the wire-bonding procedure, a spacing S1 between the frame 14 and the metallization traces 12 is reserved to prevent the capillaries of the bond wires from bumping against the frame 14 in the cleaning procedure. In the cleaning procedure, if the spacing S2 between the frame 14 and the light-sensing chip 20 is too small, it is hard to completely remove pollutants existing between the frame 14 and the light-sensing chip 20; thus, the function of the light-sensing chip 20 is influenced.
Accordingly, the present invention proposes a packaging structure of a light-sensing element and a fabrication method thereof to effectively solve the abovementioned problems.